This invention relates generally, as indicated, to conduit systems and especially to multiple duct systems for fiber-optic cables. Heretofore conduit systems have been provided with an outer conduit enclosing a plurality of inner ducts which carry the cables. The outer conduit and inner ducts are assembled from sections around twenty feet (6.01 m) in length. A conduit coupler has been provided which fits inside the outer conduit and contains cylindrical chambers for the ends of the inner ducts. Although this conduit coupler has the slip-fit feature wherein the coupler, outer conduit and inner ducts slide together at the joints, the outer seals make it difficult to install and remove the coupler.
Also the coupler has been made of a number of different parts including separate sealing members at the inner seals and outer seals. This construction has required fabrication of the different parts and then assembly of the parts which is costly and requires inspection of the coupler to make sure it is assembled correctly. The multiple part construction has also limited the positioning of the outer seal to one location and thereby limited the gripping capacity of the outer seal.